Question

18. Read the following and answer any four questions from 18 (i) to 18 (v) (1x4=4)

All the elements on the left side and in the middle of the periodic table (except hydrogen) are metals.The

metals are separated from the non-metals by a diagonal step like line that runs from Boron(B) to

Polonium(Po). Some elements that lie along the line that separates metals from non-metals, have

properties that fall between metals and non-metals. These elements are regarded as metalloids e.g B, Si,

Ge, As, Sb, Te and Po.

General properties like atomic size, valency, metallic and non-metallic characters and electronegativity

shows deviations while we move across the period and down the group. Electronegativity is a chemical

property that describes the power of an atom in a molecule to attract electrons to itself. As we move across

the period the electronegativity increases due to decrease in the atomic radius. Metallic character also

decreases across the period due to decrease in the atomic radius.

i. From the given set of metals and non-metals, identify the non-metals.

a) S, P, K

b) Mg, Al, Na

c) S, P, N

d) S, Al, K

ii. Which of the following elements will form acidic oxides?

a) Sodium

b) Magnesium

c) Aluminium

d) Sulphur

iii. Which among the following is the least reactive alkali metal?

a) Li

b) Na

c) K

d) Rbiv. A graph below represents the electronegativity of elements in the third period.

Which of the following correctly represents the decreasing order of metallic character of

elements in the third period as plotted in the graph?

a) Cl>Mg>Al>Si>P>S>Na

b)Na<Mg<Al<Si<P<S<Cl

c) Na>Mg>Si>P>Al>S>Cl

d)Na>Mg>Al>Si>P>S>Cl

(v) Identify the reason for the gradual change in non-metallic character of the elements in the third period.

a) Non-metallic character decreases as the effective nuclear charge acting on the valence shell electrons

increases across a period.

b) Non-metallic character increases as the valence electrons increases across the period.

c) Non-metallic character decreases due to the repulsion between the electrons in the valence shell.

d) Non-metallic character increases as the effective nuclear charge acting on the valence shell electrons

increases across a period.​

Answer 1

Answer:

1=c option

2=sulphur

3=li

4=b

5=b